Motorized wood cutting saws, for example chainsaws, have been used for many years to quickly cut through trees and branches, making the wood suitable for burning or disposal.
Typically, while the tree is standing, a series of cuts are made at the base of the tree trunk to cause the tree to fall. After the tree is felled, the branches are removed, which results in the tree trunk lying horizontally on the ground. The trunk of a medium or large tree can weigh thousands of pounds. Also, since tree trunks are never perfectly straight, and since the ground is rarely perfectly flat, the trunk can be supported in unpredictable ways.
Often, when an attempt is made to cut the trunk into smaller pieces, the weight of the tree trunk, and the unpredictable support can cause the saw kerf to close prior to finishing the cut. As the kerf closes, it can pinch the blade or bar of the saw, stopping the saw from cutting any deeper, and making it nearly impossible to extract the saw bar from the kerf. When this happens, an additional chainsaw is often required to cut the pinched chainsaw free. This proves to be troublesome since most woodcutters will carry only one chainsaw into the cutting area.
One method of remedying the pinching problem is to use a large pry bar (cant hook) to lift the log a few inches off the ground several feet from one end. The cut is then made on the elevated end of the trunk. This method is effective, but requires that the woodcutter purchase a relatively expensive and heavy custom tool, and carry the tool into the woods each time wood is to be cut. Also, a very large tree trunk will weigh far too much to lift even with a large cant hook.
The other standard method for remedying the pinching problem employs a plastic or metal wedge (referred to as a bucking wedge) that is driven into the saw kerf to keep it from closing. Typical logging or bucking wedges are usually 2″-3″ wide, approx 5″-8″ long, and taper from 1″ or more at the top, to a sharp edge at the bottom. Because of the relatively sharp taper of the bucking wedge, a hammer or mallet must be used to drive the wedge into the saw kerf. The draw back to the bucking wedge method is that an extra tool such as a mallet or hammer must be carried into the woods to drive the bucking wedge into the kerf. Also, since both of the wood cutter's hands are required to install the bucking wedge, the chainsaw must be stopped, and the chainsaw bar must be extracted from the kerf prior to installing the bucking wedge to reduce the possibility of injury to the wood cutter. Additionally, if the bucking wedge is driven too deep into the kerf, it will contact the blades on the top of the saw bar when it is re-inserted, resulting in damage to the saw chain or bucking wedge or both. A more dangerous result would be the bucking wedge being expelled from the kerf at high speed after contacting the chain. Examples of standard bucking wedges are shown in U.S. Pat. Nos. 4,451,024 and 5,290,012. An expandable wedge is shown in U.S. Pat. No. 4,130,270.
An anti-bind device for chainsaws is taught by King in U.S. Pat. No. 5,074,047. King teaches a number of embodiments of a device that permanently mounts to the bar of a chainsaw. The drawback to King's device is that the additional equipment mounted to the chainsaw would add a significant amount of weight to the saw, and would get tangled in brush when moving through wooded areas. Bass describes another anti-bind device, permanently mounted to a chainsaw in U.S. Pat. No. 4,534,112.
Another anti-bind device is shown in U.S. Pat. No. 3,983,915 by Steele called a “logging stop member”. Steele teaches a spacing device of uniform thickness preferably constructed from aluminum. A straight abutment member is shown attached to one side of the stop member using bolts to make the abutment member adjustable. There are a number of problems with the Steele design. Even with a method for limiting the depth at which the stop member may be inserted into the saw cut, there would always be a chance that the stop member would come into contact with the moving blade of the chainsaw. The aluminum from the stop member could significantly dull, or destroy, the chainsaw blade, requiring the wood cutter to disassemble the chainsaw to replace the blade. Also, the plurality of pieces used to construct the stop member would make the unit costly. The main disadvantage to the Steele design is that the entire unit is planar and of uniform thickness. Since every chainsaw makes a cut that is slightly different in width, a wide range of stop member sizes would have to be offered to cover the wide variety of chainsaw brands employed today. Also, since a chainsaw cut is extremely rough, every cut from the same chainsaw is slightly different, which would require a woodcutter to carry several different stop member sizes into the woods to support one chainsaw. Then during the cutting operation, there is a good chance that more than one stop member would have to be tried to find the proper size. This would require shutting down the chainsaw and removing the blade from the cut in order to insert the proper size stop member.